Avian mycobacteriosis in three horses.

This research study presents the clinical and pathological findings of avian tuberculosis in three adult horses. It details the symptoms, along with the identified gross and microscopic lesions in various parts of the horses’ bodies, and identifies the specific types of Mycobacterium avium-intracellulare complex causing the disease.

Clinical Features

• The study focuses on three adult horses suffering from avian tuberculosis, a disease commonly known to afflict birds but rare in horses.
• All the horses exhibited similar clinical abnormalities, including chronic weight loss and hypoproteinemia, a condition characterized by lowered protein levels in the blood.

Pathologic Findings

• The research provides a detailed account of the gross pathologic lesions found in the horses, including chronic enterocolitis (inflammation of the small intestine and colon) with mesenteric lymphadenopathy (disease affecting the mesenteric lymph nodes) in two horses.
• The third horse was found to have hepatic granulomas, which are mass-like lesions in the liver.

Microscopic diagnoses

• The microscopic examinations revealed chronic, non-caseating (non-necrotizing) granulomatous enterocolitis and necrotizing, non-mineralizing granulomatous hepatitis—that is, inflammation of the small intestine and liver, respectively, which are denoted by nodular inflammation but not associated with tissue death or mineral deposits.
• All three horses exhibited granulomatous lymphadenitis of mesenteric lymph nodes—meaning their lymph nodes showed granulomatous inflammation—with varying degrees of non-mineralizing, coagulation necrosis (localized cell or tissue death).

Bacterial Findings

• The researchers isolated various serotypes of the Mycobacterium avium-intracellulare complex, a type of bacteria that often causes disease in immunocompromised individuals, from selected tissues and feces of the horses.
• This finding indicates that these strains of bacteria were causing the avian mycobacteriosis in the three horses studied.